Soluble proteins and peptides can sometimes aggregate into insoluble, self-assembled filamentous aggregates including amyloid and amyloid-like structures. Current interest in amyloid fibrils and related aggregates arises from their involvement in diseases, such as Alzheimer's disease (AD), type 2 diabetes, prion diseases, and other protein misfolding disorders (Dobson, C. M. (2002) (letting out of shape, Nature 418, 729-730). Although the precursor molecule used for forming the fibril associated with each disease is different, they for the most part appear to share very similar assembly progressions and similar structural details in the aggregated forms. Data from genetic, animal models and biochemical studies suggest that amyloid beta (Aβ) plays a central role in the pathology of AD. The abnormal excessive accumulation of especially toxic versions of the Aβ peptide in the brain is a common characteristic of AD. The Aβ molecule is a 40 to 42 amino acid proteolytic product of the amyloid precursor protein (APP) resulting from the sequential cleavage by two membrane-bound aspartic proteases called the β and γ secretases, respectively (Haass, C., Koo, E. H., Mellon, A., Hung, A. Y., and Selkoe, D. J. (1992) Targeting of cell-surface beta-amyloid precursor protein to lysosomes: alternative processing into amyloid-bearing fragments, Nature 357, 500-503). Although the Aβ40 is more abundant in the blood and CSF, Aβ42 is thought to be the more toxic species (Selkoe, D. J. (1997) Alzheimer's disease: genotypes, phenotypes, and treatments, Science 275, 630-631). As Aβ is a natural product that is present in the brains and the cerebrospinal fluid (CSF) of normal human beings, its mere presence cannot be responsible for causing AD (Haas et al.; Seubert, P., Vigo-Pelfrey, C., Esch, F., Lee, M., Dovey, H., Davis, D., Sinha, S., Schlossmacher, M., Whaley, J., Swindlehurst, C., and et al. (1992) Isolation and quantification of soluble Alzheimer's beta-peptide from biological fluids, Nature 359, 325-327; Vigo-Pelfrey, C., Lee, D., Keim, P., Lieberburg, I., and Schenk, D. B. (1993) Characterization of beta-amyloid peptide from human cerebrospinal fluid, J Neurochem 6/, 1965-1968; Walsh, D. M., Tseng, B. P., Rydel, R. E., Podlisny, M. B., and Selkoe, D. J. (2000) The oligomerization of amyloid beta-protein begins intracellularly in cells derived from human brain, Biochemistry 39, 10831-10839). Instead, it is the self-assembly of Aβ that is responsible for neuronal injury. Both amyloid beta-based plaques and neurofibrillary tangles are found in AD postmortem brains. Neurofibrillary tangles are composed mainly of abnormally phosphorylated tau protein (a neuron-specific phosphoprotein that is the major constituent of neuronal microtubules). However, recent evidence show that it is the toxic forms of Aβ that might be responsible for the pathology of Alzheimer's.